New nature-mimicking freeze-casting technique

Humans have attempted to emulate nature’s approach to material fabrications through a variety of techniques that have so far proven to be time-consuming, size-limiting and costly. Some of these techniques can also be detrimental to the environment and fail to provide sufficiently precise control over the final structure. Freeze-casting, a technique in which a laboratory cold finger is used to create lamellar ice crystals that serve as a template for making biomimetic scaffolds or composites, can overcome many of these limitations. US DOE L. Berkeley Lab researchers have developed a nature-mimicking bidirectional freeze-casting technique that enables them to design and create strong, tough, porous and lightweight materials comparable to bones, teeth, shells, and wood. The research team was inspired by some sophisticated hierarchical architectures in certain natural materials that result in outstanding properties despite being porous and made from weak constituents. A paper in Sciences Advances describes this study in detail. The Berkeley researchers successfully tested their bidirectional freezing technique on particles of hydroxyapatite, a naturally occurring mineral of calcium and the main component of tooth enamel and bone mineral but it can be applicable to many other materials. The most likely applications in the shorter term will be medical implants, such as bone/orthopedic implants. The materials are stiff, strong and tough and can match the mechanical properties of bone while preventing the stress-shielding that can cause bone to atrophy.